1. Field of the Invention
The present invention relates to a method for surface treatment of plastic material, which is preferable in view of the preservation of global environment, which is easy in disposal of the treating solution used and in which the plastic material after surface treatment can have a rough surface having good adhesion to a coating film to be formed thereon, as well as to an apparatus used for the method.
2. Description of Related Art
In coating plastic materials used in the bumper, fascia, fender, etc. of automobile, it has been widely conducted to subject said plastic materials to vapor cleaning with, for example, trichloroethane in order to clean their surfaces and allow them to have good adhesion to coating films to be formed thereon. The use of trichloroethane, however, has become, in recent years, an object of regulation in view of the preservation of global environment. As a measure for this regulation, cleaning with an acidic or alkaline cleaning solution is under way using a sprayer comprising a large number of stationary headers and a large number of spray nozzles fitted to the headers (this sprayer is the same type as generally used in surface treatment of metals). This cleaning method, however, has various problems. That is, the pump capacity is large; the power consumption is high; the cleaning solution tank is large; the amount of the cleaning solution used is large; and the surface of the plastic material after cleaning tends to show insufficient and unstable adhesion to a coating film to be formed thereon.